Experimental investigation of bioceramic (Hydroxyapatite and Yttrium stabilized zirconia) composite on Ti6Al7Nb alloy for medical implants

ABSTRACT

In this experimental work, a mixture of Hydroxyapatite (HAp)+yttrium stabilized zirconia (YSZ) is deposited on a layer of Ti6Al7Nb alloy by electron-beam deposition method, which finds its application in bone and dental implants. Multi-criteria decision making method is adopted (TOPSIS) highlights the close to an ideal solution at the temperature of 160°C (Chamber), 950°C (Furnace), 30 mA (Energy), 90 min (Duration) for achieving the coated layer with optimal thickness. XRD revealed the heat treatment of the samples varying at 450°C and below, tend to shift the sample toward amorphous region due to the inherent nature of electron-beam deposition. To compensate for this, a post-heat treatment has been carried out. From SEM analysis, it is ascertained that coated specimen indicates minimal micro voids and pores, as seen in the cross-sectional area of the HAp/YSZ coated Ti6Al7Nb. The percentage increase from the stoichiometric YSZ and HAp (1.68) to 18.96% (1.99) and 19.20% (1.54) indicates the rise in elemental composition with rise in temperature, attributed to the dissolving nature of P, along with the boundaries of Zr and Ca. In the presence of HAp-YSZ, nano-coated specimen on the substrate would lead to a higher penetration depth along with increase in the strength of the bond formed (adhesive) in the specimen. In the presence of HAp/YSZ powder the corrosion rate falls by 49.34%, attributed to the presence of Zr in YSZ sample creating an addendum for osseointegration.

KEYWORDS:

• Biocoating
• corrosion
• dissolution
• EBM
• Hydroxyapatite
• Yttrium
• Zirconia